Long-eared owl (Asio otus)

Specially adapted feathers allow the long-eared owl to be almost silent when in flight

A proficient hunter, the long-eared owl catches mice in complete darkness by using sound to locate its prey

After catching its prey, the long-eared owl usually swallows its victim whole!

The long-eared owl can live up to an impressive 27 years in the wild

Classified as Least Concern (LC) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

A common and widespread species, the long-eared owl can be recognised by its orange eyes, prominent ear tufts, and rounded, buff or rufous facial disk (2) (4) (5). The plumage is a mixture of black, brown, grey, buff and white on the upperparts, and whitish-grey and buff, with dark brown streaking and barring on the underparts. The wings are long and rounded, with a buff patch on the upperwing and a dark crescent below. Other distinctive features include conspicuous white eyebrows above the eyes and a white patch below the beak, along with densely feathered legs and toes. The feathers of this species are specially adapted so that, even when beating its wings, flight is almost noiseless (2). During the breeding season, the male produces a distinctive advertising call consisting of a low "hoo, hoo, hoo” repeated 10 to 200 times, which the female responds to with a raspy buzz. When alarmed, this species will also make a barking “ooack, ooack, ooack” sound (5). There are four subspecies of long eared owl, which vary in geographical location and appearance (2).

The long-eared owl has an expansive range, extending throughout much of North America, several Atlantic Islands, Europe and Asia, as far as Japan (2). SubspeciesAsio otus otus has the largest range, extending from the British Isles and Iberia, east to Sea of Okhotsk, and south as far as the Mediterranean Islands, north-west Africa, the Middle East, the Arabian Peninsula and northern Pakistan (2) (6). In addition, isolated populations of Asio otus otus also occur in east-central China and on the Azores (6). By contrast Asio otus canariensis has the smallest range, and is restricted to the Canary Islands. The two North American subspecies both have relatively large distributions, with Asio otus tuftsi occurring inwestern Canada, south through much of the western U.S.A. to Mexico and north-west Baja California. Asio otus wilsonianus occursfrom south-central and south-east Canada, south to northern Oklahoma and Virginia (2).

The long-eared owl typically inhabits dense vegetation and open forest, situated next to open areas of grassland or shrubland. It can be found from sea-level to elevations of 2,750 metres (2).

Although the long-eared owl is a mostly solitary species, it is known to roost communally in groups of 2 to 20, and may also form small nesting colonies. This species typically hunts during the night, but often begins activity at dusk, especially during the breeding season. Small mammals form the major part of the long-eared owl’s diet, especially voles, although birds may be an important source of food in some areas. The long-eared owl is a highly proficient hunter, relying on sound to locate prey, and can even catch mice in complete darkness (2). It actively seeks out prey, flying noiselessly on a zigzag path through open woodland and over clearings and fields (2) (5). Prey is usually taken on the ground, with the long-eared owl swooping down and dispatching its victim by biting the back of the skull, before swallowing the animal whole (2).

The long-eared owl breeds between February and July. Breeding pairs are typically monogamous, although polygyny is also known to occur. Pairs normally utilise abandoned nests of other birds, but may also use cavities in trees and cliffs, or even build a nest on the ground. A clutch of five to seven eggs is laid (more if food is abundant), which are incubated by the female for 26 to 28 days, while the male supplies food. In a behaviour known as “branching”, chicks leave the nest before being able to fly and reside in surrounding vegetation, roosting separately, and thereby potentially reducing predation. While the young are capable of flight at around 35 days, both parents continue to provide food for several weeks after fledging. The long-eared owl reaches sexual maturity at around one year old, and has been known to live for up to 27 years in the wild (2).

While some populations of the long-eared owl are resident throughout the year, others make local seasonal movements in response to prey availability or even lengthy migrations. Some European breeding populations, for example, winter as far south as Egypt (2).

With an abundant population, estimated to number between 1.5 and 5 million individuals in 2009, and an extremely large range, the long-eared owl is not considered to be globally threatened (1). Nevertheless, this species has undergone a decline in Britain, which has partly been attributed to the spread of the tawny owl (Strix aluco), which has similar habitat requirements and generally outcompetes the long-eared owl (2). In North America, this species is considered to be stable, although it has shown local declines, which are probably due to habitat loss, fluctuating prey numbers and high nest predation. As such, it is listed by various North American states as Endangered, Threatened or a Species of Special Concern (2) (4).

In some parts of Britain, long-eared owls are known to use artificial baskets and open-fronted next boxes, hence it has been recommended to provide such artificial nesting structures in areas where natural nesting habitat has been reduced. In addition, land management practices to preserve grassland and nesting grounds, along with plantation of trees near open habitats would be beneficial for this species (4).